Diaphragm fuel pump with field serviceable gas filter

ABSTRACT

A diaphragm fuel pump is provided that permits field servicing of a self-contained fuel filter assembly. The filter assembly includes a screen element and supporting structure. A sheet metal dome closure is removably mounted to the pump along the supporting structure of the filter assembly and is removed when filter replacement is necessary. The dome and filter assembly combination functions as a trap for fuel vapor, providing a pulsation chamber for the inlet side of the pump.

[4 1 Oct. 14, 1975 United States Patent [191 Pfabe 3,096,722 7/1963 Fitzgerald et al. 417/471 X 3,236,383 2/1966 Smith et 210/416 X FOREIGN PATENTS OR APPLICATIONS [54] DIAPHRAGM FUEL PUMP WITH FIELD SERVICEABLE GAS FILTER [75] Inventor:

Kort K. Pfabe, St. Louis, Mo.

H W 4 a we r mF L 6 m 9 mm M 0 X E 2 n 1 P [73] Assignee: ACF Industries, Incorporated, St.

Louis, Mo.

22 Filed: Jan. 7, 1974 21 Appl.No.: 430,365

Assistant Examiner-Richard E. Gluck y. The upport- [57] ABSTRACT A diaphragm fuel pump is provided that permits field servicing of a self-contained fuel filter assembl filter assembly includes a screen element and s [52] US. Cl. 417/313; 210/416; 417/471 [51] Int. BOld 23/00; F04b 19/00 [58] Field of Search 417/313, 471; 210/232,

ing structure. A sheet metal dome closure is removably mounted to the pump along the supporting structure of the filter assembly and is removed when filter [56] References Cited UNITED STATES PATENTS 10/1932 Avigdor......s.......................

replacement is necessary. The dome and filter assembly combination functions as a trap for fuel vapor,

1,942,549 1/1934 Hampton 1,970,626 8/1934 Rockwel 3,050,189 8/1962 Williams............................

U.S.' Patent 00. 14, 1975 Fig. 2

DIAPHRAGM FUEL PUMP WITH FIELD SERVICEABLE GAS FILTER BACKGROUND OF THE INVENTION This invention relates to a diaphragm pump suitable for pumping fuel to an internal combustion engine and more particularly to a fuel pump having a field serviceable self-contained fuel filter.

An automotive vehicle conventionally has a fuel pump mounted in the engine compartment, generally some distance from the fuel tank of the vehicle. A fuel line extends between the fuel tank to the inlet side of the fuel pump. The outlet side of the fuel pump is connected to the carburetor of an internal combustion engine, for example. In order to improve the efficiency of the diaphragm fuel pump, it has been found that pulsation chambers or vapor domes may be utilized to dampen the rapid pulsations of the pump so that the fuel in the inlet conduit to the pump and the outlet conduit to the carburetor move more evenly. The U.S. Pat. No. 3 ,096,722, issued July 9, 1963, to Fitzgerald et al., sets forth a detailed description of the function and use of such vapor domes. In general, the vapor dome portion of the pump structure is an integral, sheet metal manufacture formed into a predetermined configuration and attached to the remaining pump structure in a liquid seal relationship. The vapor dome portion conventionally is not intended to be removable after its assimilation in the pump structure.

Certain applications for diaphragm fuel pumps have demonstrated the need for including a fuel filter in conjuction with the fuel pump. Although a self-contained filter element is a desirable feature in fuel pump systems, the filter has a tendency to become clogged unless the filter is removable in application use.

Prior to the invention disclosed hereinafter, the combination of a field serviceable fuel filter in a fuel pump using pulsation chambers in its operation was not generally believed feasible because no one had conceived a commercially acceptable method for providing pulsation chambers for the fuel pump while providing a removable filter in the pulsation chamber. Nor had anyone conceived a low cost, field serviceable filter assembly adapted for use as an important part of the pulsation chamber operation.

My invention overcomes these prior art deficiencies by utilizing a unique filter construction that serves a variety of functions. The filter assembly is designed so that the vapor dome for the inlet side of the pump structure may be mounted to it. The filter member of the filter assembly, in addition to its normal filtering function, provides the vapor trap permitting the dome to dampen the rapid pulsations of the pump. In the preferred embodiment, the filter assembly is plastic and provides support for the filter element by a unique construction technique such that the filter element is integrally formed with the remaining filter assembly structure.

One of the objects of this invention is to provide diaphragm fuel pump having a field serviceable fuel filter.

Another object of this invention is to provide a fuel pump and filter therefor in which the fuel filter forms the vapor barrier in a pulsation chamber.

Yet another object of this invention is to provide a field serviceable fuel filter for a diaphragm fuel pump in which the supports for the filter element and the filter element itself are integrally constructed.

Other objects of this invention will be apparent to those skilled in the art in light of the following description and accompanying drawings.

SUMMARY OF THE INVENTION In accordance with this invention, generally stated, a diaphragm pump has a field serviceable filter assembly mounted along the inlet side of the pump structure. The filter assembly is designed to aid in the attachment to the pump of a removable dome casing. The filter assembly and dome together form a vapor trap and pulsation chamber for the pump.

In the preferred embodiment, a unique filter assembly construction is utilized wherein the supporting elements for a filter element and the filter element itself are integrally constructed.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings, FIG. 1 is a view in side elevation, partly broekn away and partly in section, of diaphragm pump of this invention;

FIG. 2 is an enlarged view in side elevation, partly broken away and partly in section, ofa second embodiment for the inlet side of the pump shown in FIG. 1;

FIG. 3 is an enlarged view partly in section and partly broken away, for the inlet side of the pump shown in FIG. 1; and

FIG. 4 is a plan view of a filter assembly taken along the line 4-4 of FIG. 3, the associated pump structure being eliminated for drawing simplicity.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to FIG. 1, reference numeral 1 indicates one illustrattive embodiment of diaphragm fuel pump of this invention. The embodiment illustrated is a so-called inverted pump, that is, its inlet and outlet are located at the bottom of the pump. The pump 1 includes a conventional rocker arm housing 2 defining a flange 3 for attaching the pump 1 to an internal combustion engine, for example, not shown. A rocker arm 4 is free to pivot about a pin 5 which is mounted to the housing 2, permitting rocking motion of the arm 4 on an axis transverse to the housing. Rocker arm 4 has a first end 6 and a second end 7. When the pump 1 is mounted on an internal combustion engine, for example, the end 6 of the rocker arm 4 is engaged by an engine driven cam, not shown. Movement of the cam causes the end 7 of the rocker arm 4 to reciprocate against the bias of a spring 8.

The spring 8 extends between an'upper cup-shaped spring retainer 9 formed in the rocker arm housing 2 .and a spring keeper 10. The keeper 10 is U-shaped in and.the neck of the keeper 10 in a slip fit. Other connection techniques work well and are compatible with the broader aspects of this invention.

A hollow, conical pump body 12 is integrally formed with the rocker arm housing 2 and extends downwardly from it. An opening 13 is provided between the interiorv of the rocker arm housing 2 and the pump body'12 at the top of the latter. The pump body 12 has an outwardly projecting rim 14 at its lower extremity. The rim l4 constitutes a seating surface for a margin of an annular diaphragm 15. The diaphragm 15 is conventional and commonly is constructed from a relative thin disc of flexible fuel resistant material, such as suitable synthetic rubber, which, when in unstressed condition, is flat or substantially flat. The outer margin of the diaphragm 15 is clamped against the rim 14 by a pump cover 16. Pump cover 16 preferably is a one piece, thin walled sheet metal construction, formed in a shallow cup shaped design, having a bottom or end wall 17 and a flairing, rounded annular peripheral wall 18 which together with the pump body 12, defines a pumping chamber 19. The outer edge of the wall 18 is crimped over the rim 14 with the margin of the diaphragm 15 under sufficient pressure to provide a fuel tight seal between the rim 14 and wall 18.

The diaphragm 15 is adapted to be pulled or flexed upwardly by the diaphragm actuating rod 11 and to be flexed downwardly by a spring 20. The rod 11 extends through the opening 13 into the rocker arm housing 2. The rod 11 is slidably mounted through an oil seal and rod guide 21, which is held in and against an annular shoulder 71 at the juncture of the pump body 12 and the rocker arm housing 2 by the reaction of a seal retainer ring 22 and the spring 20. The sping preferably is a coil compression sping surrounding the rod 11.

.The diaphragm 15 is mounted to the lower end of the rod 11 between an upper circular plate 24 and a lower circular plate 25. The upper plate 24 is formed with an annular corrugation rib, not shown, which forms a seat for confining the lower end of the spring 20. Preferably, the upper plate 24 is ofa larger diameter than the lower plate 25 so as to provide a rim 26 constraining the diaphragm to have an annular, free, nonreversing loop 27. The lower plate 25 has a curved rim 28 engaging the loop 27. In the downward position of the diaphragm illustrated in FIG. 1, the outside of the loop 27 engages the wall 18 of the pump cover 16. When the arm 4 is rocked in the operation of an internal combustion engine, for example, it lifts the rod 11 and pulls the diaphragm 15 upwardly. This loads the spring 20 and permits that spring to drive the diaphragm and rod downwardly prior to rocker arm 4 activation on a succeeding cycle.

The sheet metal pump cover 16 is formed with an integral, deep-drawn rounded bottom cylindrical cup shaped projection 29, extending downwardly from the bottom wall 17 of the cover 16. The projection 29 defines an outlet passage or discharge cavity for the pump 1. Projection 29 has an outlet nipple 30 attached to it by any convenient method. Brazing works well, for example. The nipple 30 provides a connection means for connecting the pump to an inlet side of a carburetor structure for internal combustion engine, not shown. The projection 29 houses a discharge check valve, also not shown, but which is similar to an inlet check valve 31 later described in detail. In addition, the projection 29 houses means for enabling the outlet side of the pump 1 to function as a pulsation chamber for the outlet side of the pump 1. The use of pulsation chambers are known in the art and such chambers are described in the above referenced U.S. Pat. No. 3,096,722 to Fitzgerald et al. Reference may be made to the Fitzgerald et al patent for specific details of pulsation chambers not forming a part of this invention. It should be noted that it is conventional to provide a screen in both the inlet and the discharge cavity of fuel pumps as important parts of pulsation chamber operation. These screens commonly are of a flat circular form and are intented to be nonremovable. The screens are constructed from large mesh size material and generally do not operate nor are they meant to function as fuel filters for the pump. However, these screens do function as a vapor barrier for trapping fuel vapor and, as indicated, are important in the operation of the pulsation chambers.

The pump structure described above is substantially conventional and the pump 1 of this invention differs from prior art devices in the construction of the inlet side of the pump. The bottom wall 17 of the pump cover 16 has a downwardly extending annular lip 32 integrally formed with it. The lip 32 defines a seat for a cylindrical extension 33. The extension 33 is attached to the pump cover 16 by any convenient method. Brazing or welding works well. As its name implies, the extension 33 generally has a cylindrical shape, formed from a wall 75. The wall defines a radially outwardly extending flange 34 along a first end of the extension 33, and defines a radially inwardly extending annular shoulder 35 along a second end of the extension. The flange 34 aids in attaching the extension 33 to the pump cover 16 while the shoulder 35 delimits a seat for the inlet check valve 31.

Check valve 31 is conventional and generally comprises a valve seat 36 and a mushroom head 37 on a stem extending from the valve seat, with a spring pressing a disc valve member toward the seat. The valve seat 36 is press fitted within the extension 33 so as to abut the shoulder 35. The check valve of the discharge cavity is, of course, positioned oppositely with respect to the check valve 31.

The preferred structure for providing a field serviceable fuel filter in the inlet side of the pump 1 is shown in FIGS. 1 and 3. In the construction there illustrated, a fitting 38 is attached to the extension 33 outboard of the shoulder 35. The extension 33 and the fitting 38 may be interconnected in a variety of techniques. Brazing, a press fit or welding are acceptable methods, provided that a liquid seal is maintained between the fitting 38 and the extension 33.

Fitting 38 includes an annular surface 39 and a longitudinal side wall 40 that terminates in a radially outwardly extending boss 41. The surface 39 has a plurality of openings 58 through it, symmetrically arranged about a central hub 42. The hub 42 has an axial opening 43 through it. Hub 42 is sized to receive a shank portion 76 ofa conventional threaded fastener 44. The internal diameter of the opening 43 may be provided with complimentary threads to facilitate interconnection with the shank portion 76. A seal 45, in the form of a conventional O-ring, is mounted over the external diameter of the fitting 38 and abuts the boss 41.

A sheet metal dome structure 46 has a first, flaired end 47 and a second, substantially closed end 48. The flaired end 47 is designed to receive the boss 41 in a slip fit and bears against the seal 45 in the mounted position of the dome 46 with sufficient pressure, under the influence of fastener 44, to provide a liquid seal about the external diameter of the fitting 38. The end 48 of dome 46 has a central receptacle 49 formed in it, designed to receive an O-ring 50 and a head 77 of the fastener 44. Receptacle 49 has a central opening through it for permitting passage of the shank 76 of the fastener 44 prior to fastener insertion through the receptacle 49, the O- ring 50 providing a liquid seal between the shank 76 of the fastener 44 and dome 46. The dome 46 includes a side wall 51jhaving an opening in it sized to recive an inlet nipple 52. The nipple 52 may be integrally formed with the dome 46 or the dome and nipple may be manufactured separately and later connected by any convenient method.

A filter assembly 53 is removably mounted within a chamber 78 defined by the dome 46, between the end 48 of the dome 46 andthe surface 39 of the fitting 38. Filter assembly 53 preferably has a broad, annular base 54 forming a first end of. the assembly. The base 54 has a central open area 80 in it. A plurality of support ribs 55 are integrally formed with the base 54 adjacent the open area and project upwardly from the base 54, as viewed in FIG. 4. The ribs 55 extend between the base 54 and an annular flange 56 forming a second end of the assembly 53. The ribs 55 are approximately parallel to one another along the flange 56 portion of the as sembly 53. The flange 56 has a smaller outer diameter than the open area 80 so that the filter assembly resembles a frustum when viewed in cross-section, a view corresponding to FIG. 3. In the preferred embodiment, four of the ribs 55 are spaced at ninety degree increments about the open area 80 in the base 54. A screen element 57 extends circumferentially between the ribs 55 and axially between the base 54 and the annular flange 56. The screen 57 is conventional and may comprise a variety of mesh sizes, provided the mesh is capable of performing a filtering function.

The approximately parallel relationship of the ribs 55 along the flange 56 enables the flange to receive the receptacle 49 in a slip fit. The fastener 44 may be tightened in the opening 43 so that the filter assembly 53 abuts the surface 39 and the dome 46 tightly. Consequently, fuel entering the pump 1 along the inlet nipple 52 necessarily passes through the screen 57 before proceeding through the area 80 of the base 54 and the openings 58 in the surface 39.

In the preferred embodiment of this invention, the filter assembly supporting structure, which for the purposes of this specification includes the base 54 and the ribs 55, is a molded plastic device constructed from any of a variety of suitable chemical or other derivatives. The attachment of the screen 57 to the ribs 55 is unusual in that the screen 57 is molded integrally with the support ribs 55 so that screen 57 is both supported by and attached to the ribs 55. Consequently, no other means for attaching the screen 57 to the ribs 55 or base 54 is required. Such construction gives a particularly low cost filter assembly which may be replaced merely by removing the fastener 44 and extracting the filter assembly 53 from the dome 46.

The area between the dome 46 and the filter assembly 53, indicated generally by the numeral 60, constitutes a trap in which fuel vapor, as distinguished from liquid fuel, may be collected. The screen 57, in addition to its filtering function, serves the purpose of effectively trapping the gaseous bubbles of fuel vapor and air in the area 60 without impeding rise and fall of the level of liquid fuel. In this respect, it is to be observed that the pressure required to force the vapor and air through the screen 57 is higher than the pressure required to force liquid through that screen. While the exact technical reason for this occurrence is unclear, it appears to be due to the surface tension of the bubbles of fuel vapor and air in the area 60 and/or to the tendency of liquid fuel to cling within the intertices of the screen 57 due to surface tension of the liquid fuel, thereby tending to block flow of fuel vapor and air. In any case, the screen 57 acts to hold the fuel vapor and air bubbles within the area 60 at maximum bubble volume, and this assures maximum pulsation dampening efficiency. v

A second embodiment of fuel pump having a field serviceable fuel filter is illustrated in FIG. 2. In this em bodiment, a filter support structure 61 is integrally formed with the lip 32 of the bottom wall 17 of pump cover 16. The support structure 61 has an annular base ,portion 62 which defines a first seat 63 for the O-ring 45 on a one side of the base portion 62, and a second seat 81 for the inlet check valve 31 on a second side of the base portion 62. The structure 61 has a plurality of screen supporting ribs 64 extending downwardly from it, as viewed in FIG. 2, between the base portion 62 and an end 65 of the structure 61. The end 65 is formed to define a receiver 66, which is designed to receive a shank portion 67 of a fastener 68 in interlocking relationship. Fastener 68 performs the same function with respect to dome 46 in the embodiment of FIG. 2, as fastener 44 performs in the embodiment of FIG. 3. Dome 46 and the rings required to seal it to the pump 1, while exhibiting a dimensionally different silhouette in FIG. 2, structurally are exactly equivalent to the embodiment shown in FIG. 3, and are not described in detail. Like reference numerals for like components are utilized, where appropriate.

A removable filtering screen 69 is mounted over the filter support structure 61 and extends between the base portion 62 and the receptacle 49 of the dome 46. The O-ring 50 is mounted over the shank 67 of the fastener 68 and provides a liquid seal between the dome and fastener 68. Again, tightening the fastener 68 within the receiver 66 forces the dome 46 against the O-ring 45, and compresses the O-ring 50 between the head of the fastener 68 and the dome 46. In this embodiment, removal of the dome 46 by withdrawal of the fastener 68 from the receiver 66 permits removal of the filtering screen 69.

Again, the screen 69 resembles a frustum, and has a mesh size sufficient to enable it to filter particles from the liquid fuel prior to entrance of the fuel to the pump 1. Operation of the screen 69 and structure 61 as a vapor trap is substantially as that described above.

It is thus seen that the several objects of this invention are achieved and other advantageous results obtained.

Numerous variations, within the scope of the appended claims, will occur to those skilled in the art in light of the foregoing description and accompanying drawings. Thus, as evidenced in the drawing, the sil houette of the dome 46 may be varied. Various materials may be substituted for those discussed in conjunction with various component members of the pump structure. Other designs for the filter assembly 56 may be utilized. For example, while the support structure for the screen in each of the embodiments illustrated was described as a frustum, other geometric designs are compatible with the broader aspects of this invention. Likewise, the ribs may meet the base of the filter assembly 53 or structure 61 at exterior angles different from those shown. These variations are merely illustrative.

I claim: 1. A diaphragm pump comprising:

a pump body, said pump body including a pumping chamber;

a diaphragm closing said pumping chamber;

means for reciprocating the diaphragm in response to a predetermined stimulus;

a formed casing attached to said pump body outboard of said diaphragm, said casing clamping at least a margin of said diaphragm between said casing and said pump body, said casing having an outlet cavity integrally formed therewith, said outlet cavity having an outlet check valve mounted therein, said casing also having an inlet cavity assembly removably mounted to a lip extending from said casing on the same side of said diaphragm as said outlet cavity, said lip including an inlet check valve mounted therein, said inlet cavity assembly including a dome structure and a disposable filter, means for removably mounting said inlet cavity assembly insertable through said dome and said disposable filter; and

a plurality of ribs integrally formed and extending outscreen element is a frustum. 

1. A diaphragm pump comprising: a pump body, said pump body including a pumping chamber; a diaphragm closing said pumping chamber; means for reciprocating the diaphragm in response to a predetermined stimulus; a formed casing attached to said pump body outboard of said diaphragm, said casing clamping at least a margin of said diaphragm between said casing and said pump body, said casing having an outlet cavity integrally formed therewith, said outlet cavity having an outlet check valve mounted therein, said casing also having an inlet cavity assembly removably mounted to a lip extending from said casing on the same side of said diaphragm as said outlet cavity, said lip including an inlet check valve mounted therein, said inlet cavity assembly including a dome structure and a disposable filter, means for removably mounting said inlet cavity assembly insertable through said dome and said disposable filter; and a plurality of ribs integrally formed and extending outwardly from said lip, said ribs having a free end defining a receptacle for receiving a threaded fastener, said fastening means comprising a threaded fastener, said disposable filter comprising a screen element slidably mounted over said ribs.
 2. The diaphragm pump of claim 1 wherein said screen element is a frustum. 